Yaks and similar types are not fast aircraft. Some people who fly them simply like to think they are. However, these aircraft can be operated safely at quite slow speeds even when in formation. Speed is not an issue.
The simple thing about a run and break is that it is not a civil procedure, it is not published in any civil document and there are no civil R/T procedures for the reporting of such a manoeuvre.
That does not legally prevent one from doing a run and break. Just as it does not prevent a pilot from completing an aerobatic sortie over an airfield. Airmanship may say something different!
However, the law does provide protection to aircraft in the circuit at an airfield. Any aircraft on a run and break is clearly not conforming to the circuit and thus simply has to avoid the circuit traffic. The circuit traffic simply continues with the standard circuit and does not alter the circuit to accomodate the run and break aircraft because they will avoid the circuit.
If anything goes wrong when a run and break is in progress then the leader and wing flights are guaranteed to be responsible provided that the other aircraft have continued to fly the standard circuit.
There is no reason why a run and break can not be done on the dead side at or above circuit height and the aircraft stream over the upwind end of the runway and join downwind as everyone else does. There would be no unusual calls and no need for anyone else to hear or worry about something they do not understand.
There is no other way to look at the run and break at or below circuit height over the active runway other than as a show-off exercise. Something that proper formation training and aerobatic training tries to get pilots to avoid.........unless they have a display authorisation and then that even impresses that the pilots should not simply show-off!!
To sum it up - ignore run and breaks - as far as GA pilots need to be concerned they do not exist. Pilots completing a run and break will avoid the circuit and accept responsibility for anything that goes wrong. Thus the simple answer is - ignore run and breaks.
Regards,
DFC